The present invention relates to a motor installed in an electrical apparatus, and more particularly to terminal assemblies for attaching an end of a coil wound around a stator core of the motor.
In general, a brushless motor includes a stator substrate for securing a stator, and this stator substrate typically has the next structure. The stator substrate is configured with a so-called printed wiring board which includes a base typically made of an iron sheet; an insulating layer covering the base; a conductive layer typically made of copper foil patterned on the insulating layer; and a resist layer covering the conductive layer and insulating layer. In the conventional brushless motor, a motor coil end is soldered to this printed wiring board.
Another conventional brushless motor that does not use a printed wiring board as described above employs a metal sheet as the substrate to which the stator core is secured. A conductive pattern having a raised portion with groove is formed on this metal substrate. The stator core around which coils are wound via insulators is secured onto the substrate, and each coil end is attached to the groove on the conductive pattern, typically by press fitting. This structure is disclosed in Japanese Laid-open Patent No. H7-59288.
In a conventional step motor, the coiled core and terminal assembly to which the coil end is connected are resin-molded. Resin molding enables the placing of a housing case to cover the entire motor rim and secures the terminal assembly onto the housing case. This structure is disclosed in Japanese Utility Model No. 2534683.
The above structure using the printed wiring board is advantageous for a brushless motor which require a sensor attachment. In particular, this structure is effective for a case requiring complex wiring patterns. However, such a printed wiring board is expensive, and it is difficult to provide a step on the substrate due to its structure. Accordingly, the brushless motor employing the printed wiring board is limited to flat shapes. Moreover, this structure requires a special emphasis on reliability including avoiding damage to a board surface.
The motor employing a substrate on which conductive patterns are formed by processing a metal sheet as disclosed in Japanese Laid-open Patent No. H7-59288 has the following disadvantage. The shape of the substrate needed for securing a core becomes extremely complicated. In order to maintain the rigidity needed to endure impacts and vibration, the substrate requires a certain thickness in addition to a complicated substrate shape, which is unsuitable for thin motors. Moreover, processing of the substrate is relatively difficult, and thus the accuracy of the substrate itself is not easily assured. Accordingly, this type of motor has a considerable disadvantage to be used in small precision motors requiring strict accuracy. The method of securing a coil end to the raised portion with a groove is also unsuitable for a small and thin precision motor due to the height of the raised portion and the space between teeth of the stator core.
In a brushless motor, unlike the step motor, it is impractical and costly to cover the entire outer rim, including the terminal assembly, by resin molding. When using solder to attach the coil end in the terminal assembly with a sheet terminal, it is difficult to control the solder volume. Accordingly, this type of the terminal assembly is unsuitable for the small precision motor which do not have sufficient space allowance.
The present invention addresses the above disadvantages, and aims to offer a motor having a terminal assembly which only requires a small connection area, this terminal assembly in the motor, and an electrical apparatus which employs this motor.
The motor of the present invention has a core with two or more coiled teeth, a base for securing the core, and lands for attaching coil ends, and includes the terminal assembly which is secured to the base by welding.
The terminal assembly of the present invention includes an upper terminal holder which is an insulator, a terminal which is a conductor, and a lower terminal holder which is also an insulator. The terminal assembly of the present invention is configured by assembling at least the above three components.
The electrical apparatus of the present invention includes a casing and a motor installed in the casing. This electrical apparatus has the above motor structure and the above terminal assembly structure.
The above structures offer a motor with an inexpensive and easily assembled terminal assembly having a small connection area, the terminal assembly, and an electrical apparatus employing this motor.